Why is sex everything now? Why is it so wrong to wait till marriage?? I am a 19 year old female, and I use to?

be really crazy back in highschool with parties and all and I was a trouble maker too and had many bfs and all that, but I never lost my virginity because I feel that is something that should be kept for marriage. I use to be a little player and I did mess around doing other stuff for my pleasure but not sex sex. Now, I did grow up and get more religious. I am trying to be better, as far as being faithful and all. My "friends" think I am crazy and even a liar for saying I'm a virgin because they don't believe me. They say I'm dumb for waiting till marriage too and they see no legit reason to do so. Why are so many people okay with premartial sex?